The invention relates to a heat exchanger arrangement, especially for the independent heating of the driver and passenger sides of a passenger compartment of a motor vehicle.
The invention is especially concerned with heat exchanger arrangements of the type including two tube/fin heat exchanger block units separated from one another, but arranged at common upper and lower liquid cooling (e.g., water) boxes or tanks. The tube/fin heat exchanger block units include a plurality of fins extending perpendicular to the tubes, whereby heat exchange between air flowing past the tubes and fins and the water in the tubes takes place. Water intake and return connectors are arranged at the respective tanks.
Heat exchangers are disclosed in DE OS (German Published Unexamined Application) No. 15 51 509 including two separate heat exchange circuits passing through a common heat exchanger. In order to prevent the interference of the one heat exchange circuit by the other, the heat exchange fins of the two heat exchange circuits are separated from each other by means of a gap, which gap is formed respectively by means of slots in the fin bodies, which slots are stacked with respect to each other to compose a unit. Such heat exchangers have the disadvantage that to a certain degree the mutual interference of both heat exchanger circuits can not be prevented. It is further disadvantageous that the heat exchanger in this arrangement includes only one pipe being passed through by the heat medium, which in turn has to be connected with the heat circulation at both of its sides. The same is true if said heat exchangers are supplied with several pipes.
There are other known heat exchangers of the above mentioned type which, however, are attached only by one side with the connectors due to structural reasons. Both the intake and return connectors are then arranged at the upper water box, and the intake pipes or tubes extend downward from respective regions of the upper water box divided by separating walls to the lower water box within the common intermediate space of the heat exchangers. However, these constructions display the same disadvantages of mutual interference of heat exchange circulations.
It is therefore an object of this invention to reduce the thermal interference between the heat exchange circuits. The invention provides, in connection with a heat exchanger of the type described above, that the intake pipes extend parallel to each other to the lower water box without touching the fins. This contactless feature is obtained according to preferred embodiments by providing that the passage openings of the intake pipes which are arranged in the fins and within the common intermediate space, are of a greater diameter than the intake pipes themselves. These embodiments have the advantage that the compact structure of the fin blocks is retained and common tooling can be utilized for the manufacture of the heat exchanger. The cooler region return tubes at the upper water box are influenced only very little by the same areas of the hot intake pipes, since the same do not come in contact with the heat exchange fins.
However, it is also contemplated to form the intermediate area as a gap between partitioning walls which are provided at the edges of the fins or fin blocks at the respective heat exchange circuit units facing one another. Such partitioning walls are produced according to especially preferred embodiments by adjoining fins having edges bent to one side and which overlap each other like roof shingles. This embodiment exhibits the advantage that the intake pipe are entirely separated from the fins. In order to avoid the heating up of the air stream flowing past the intake pipes, so that such heated air stream transfers heat to the fins or the partitioning walls, it is advantageous to provide the common intermediate space with a covering means facing the side exposed to the air stream flow. The gap between the partitioning walls of the fins or these areas containing the intake pipes which areas are covered towards the air intake side, is to be chosen as small as possible in order not to reduce the heat exchange surface unnecessarily. In this connection combinations are also contemplated with intake pipes which extend by means of passage openings having a greater diameter in the area of the fin ends. Thereby the area without fins and also not participating in the heat exchange, between the separated heat exchanger units, is selected as small as possible without however, excessively increasing the danger of heat interference by increase of the intake pipes.
The cover provided along the side of the intermediate gap area of intake tubes, and being exposed to the air stream, is fixedly attached to the intake pipes in a very simple manner. In the embodiments where the intake pipes extend within the intermediate gap in between the fin blocks, the cover or mantel piece preferably is formed of a plate or panel corresponding in size to the height of the pipe fin blocks, including protruding latches at the intake pipes which are advantageously arranged to allow a lateral sliding and locking.
In order to keep the space requirement for the intake connection between upper and lower water boxes as small as possible, so that the heat exchange between the adjoining pipe fin blocks is kept to a minimum with the smallest possible work space, a further advantageous feature of the invention is to provide the intake pipes with a greater cross-section (diameter) than the return pipes of the fin blocks. This embodiment advantageously maintains the compact structure of the tube fin blocks. The common intermediate gap between the pipe fin blocks which is formed by adjoining fins having edges bent to one side and which overlap each other like roof shingles has the advantage that wider intake pipes extend entirely separate from the fins.
By utilizing this embodiment it becomes possible to arrange two intake pipes one after the other in the air stream direction, because the cross-section of the flow is adjusted to the total cross-section of the return flow. Thereby, the gap between the pipe fin blocks is minimized to an optimum. This gap is then closed, by means of a cover piece, towards the direction of air flow, thereby eliminating an interference of the two pipe fin blocks by the air stream which is heated up along the intake pipes.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, embodiments in accordance with the present invention.